Glassing over a wood mast

[popeyethesailor]

Hi all,

I have a wood mast that has bent and lost it's column strength over its 30 years.

It is 34 ft long. It starts out as about 4x6 and then tapers at the top to about 3x4. When I sail jib and jigger it bends fore and aft so much that it tries to collapse.

I wonder if I could sand off the paint and put fiberglass or carbon fiber over it to give it back the stiffness it needs? Or would it be better to have an alluminum mast?

Thanks

[NormMessinger]

Doubtful. Glass strength is in tension, not compression.

--Norm

[Scott Rosen]

What Norm said. I can't think of any good reason to glass a wooden mast.

[mtlake]

I had a boat with a mast that was glassed in 1959 when new . It broke in 1990 with no warning. Water had gotten in and you could not tell. Glass on a mast is always a bad idea. Steve

[Joe ( Cold Spring on Hudson )]

Um I disagree I think if the mast is old you may give it back some strength not by using glass, but by sanding the mast and using a thinned epoxy. Heat the wood with a hair dryer as you apply the thinned epoxy. Let the epoxy be drawn into the wood through capillary action strap and brace the mast in a strait position and let the epoxy cure I think that will definitely help the mast. I did that with a mast from a 1954 Dyer Dhow sailing dingy and it made a word of difference in mast rigidity and trueness

[WFK]

This idea rates right up there with glassing over a traditionally planked boat. Don't do it!!

[imported_Ola Sylwan]

Popeye,
Welcome to the Forum.

You can do the fiberglass stuff but you would end up with a mast full of rotten wood. :eek:

Build a new wooden mast, it is not that difficult.

Two different ways of mast building:
Mast 1 (http://sailingsource.com/ice/articles/mast_made_easy.htm)
Mast 2 (http://users2.ev1.net/~fshagan/mastm.htm)

[TomRobb]

Is it possible that it isn't rigged properly? Or is it free-standing (hard to imagine an unstayed mast not bending under load)?

[John Gearing]

Firstly, I second Tom Robb in questioning whether the mast is stayed properly. Wood tends to be fatigue-resistant, in my experience, and should not become whippy like that.

My guess is that this is a hollow mast?
What system of spreaders and/or jumpers does it employ?
Does it have a permanent backstay? Running backstays?

If the mast is some kind of box-section hollow structure, is it possible that the joints have let go to the point that pieces can move relative to each other?

I think you could stiffen this mast (assuming that's what it needs rather than proper rigging or more basic repair) by taking the finish down to the wood, painting on an epoxy sealer, and then epoxying unidirectional carbon fibers/cloth running the length of the mast. Lots of fibers, each one being full length. The folks at Gougeon Bros (of the W.E.S.T. System )used to sell carbon fibers and can probably fix you up. As noted above, fibers are strong in tension, not in compression. But when your mast bends, the surface of the concave side is in compression and the surface of the convex side is in tension. With carbon fibers applied to all sides of your mast, no matter which direction your mast tries to bend, the fibers on the opposite side will be in tension and will resist the bending force. If fore and aft bending is your only concern, you could apply the carbon to just those surfaces. Wheher carbon fibers applied in this manner will sufficiently stiffen your mast to avoid the problem you are having is difficult to predict. You should pull your mast and examine it very carefully for any structural problems it may already have. And double-check the rigging plan. And then if you still want to go the carbon route, I'd contact Gougeon Bros and ask them for some expert opinion.

Just my 2 cents.....

[Bob Cleek]

You know, some people maybe shouldn't bother with wooden boats... NO... you aren't going to do anything productive glassing a mast except hasten its rotting, which is productive only because it will prevent you from sailing the boat and maybe killing yourself. Wooden masts are hugely over engineered, compression-strength-wise. If she is whipping around, it is unquestionably a rigging problem, not that your wooden mast has lost its "compression strength," which, as a concept, is utter BS. As for soaking it in epoxy to "strengthen it"... well, that goes in the file marked "ultimate horse****."

[reddog]

Popeye:
Sounds like a rigging problem to me.Is it a fractional or masthead rig?Backstays,running or fixed,in place?
As far as glassing the mast or trying to strengthen it with epoxy,don't bother.Put your energy into making a new one if it comes to that.
Good luck:Earl

[WFK]

I don't know Bob, I think you should tell us how you really feel!
Bill

[Cecil Nickerson]

He has, check the thread on Knarr masts. Yer the best Cleek :D

Cecil

[mariner2k]

Pretty harsh Bob. Give em a break, let him learn.
25 years ago my question may have been just as foolish.
mariner

[NormMessinger]

There are more than one way to say the same thing. Which is more effective, mine "Doubtful. Glass strength is in tension, not compression." or Bob's.

But the advice I'd like to see explored further is John Gearing's carbon fiber. A boat engineer, John Fox, that used to hang out on the Compuserve sailing forum advised against it's use because the modulus of what ever was not compatible with wood. Not being an engineer I didn't understand what John was saying at the time and so much time as passed all that remains is a suspision that would preclude me from using carbon fiber on a spar. I'm talking a new spar here not popeye's. I think the question was about laying a rove of glass or carbon in the bottom of the grove in a birdsmouth spar. Yes? No? Why?

--Norm

[Bob Cleek]

Yea, well, sometimes I don't get to a post before my third Jack Daniel's and I guess it shows! LOL

[rickprose]

you could make a new mast quicker and more cheaply than applying some space-age goop and googe, at least i could, so why bother. for that matter, why bother with fiberglass at all? why not wrap the stick in strips torn from old blankets and soak them in polyester resin? what about winding duct tape around and around it from step to truck, and sprinkling some fairy dust on it, for good measure?
or pvc pipe, hose-clamped every few inches. that should do the trick...

[Frank Wentzel]

Norm

The reasoning behind not attempting to reinforce one structural member with another is simply that the material with the highest modulus of elasticity will take all the strain until it fails. Then the next highest modulus component takes over.

Lets say that for a given wooden spar, a force of 100 pounds will cause it to deflect 10 inches. Now we reinforce the spar with something (graphite fiber ?) with 10 times the modulus of wood. We will calculate the quantity graphite to yield have the same strength as the wooden spar because we want to double the strength of the spar.

Upon applying our 100 lb. force the graphite will only permit the mast to deflect 1 inch. However, almost the total strain is taken by the graphite alone because the wood has not flexed enough to develop any appreciable resistance to deflection. If we continue to increase the bending force, the graphite in the spar will finally fail at a force just over the calculated failure point for the graphite component alone. This is because the wood still has not flexed enough to begin taking up some of the load.

You will note in any composite structure there are only two active components. The high modulus component – cellulose in wood, or the glass in fiberglass – and a low modulus binder – lignin in wood or resin in fiberglass. The strength of the structure is derived almost solely from the high modulus component. A wooden mast is already a composite. If we want to use a higher modulus reinforcement then we must use enough of it to take the entire intended load. Thus a few strands of graphite incorporated in a bird-mouth mast will not make an noticeably stronger spar. I know many people have tried it and they believe it works but as Bob (The Terminator) Cleek says, spars are already over-engineered.

For a quick comparison here are some typical MOEs:
Western Red Cedar --- 1.1Mpsi
Douglas Fir --- 1.6 Mpsi
White Oak --- 1.3 Mpsi
Glass --- 6.1 Mpsi
Aluminum --- 10 Mpsi
Steel --- 30 Mpsi
Graphite Fiber --- 20 to 80 Mpsi

/// Frank ///

[NormMessinger]

By jove, Frank, I believe I've got it. For now.

Thanks.

--Norm

[mariner2k]

Yeah I know Bob, Captain Morgan and I have a similar relationship. Gotta wash it down with a Guiness sometimes.
mariner

[John Gearing]

Gee, I wonder if Popeye will ever risk asking an innocent question here again, what with the vituperitiveness of some of the responses. (of course, I have to wonder, since "Popeye" has also been a nom de plume of our own dear Bob C....did he set himself up as a straw man??).

Bob, I think you may have erred in dismissing Joe's suggestion, in that the Gougeon Bros for years have reported tests (admittedly their own) that showed that epoxy saturation alone does increase the stiffness of wood. The idea is that the part of the wood that becomes saturated becomes a different (in the sense that wood alone is already a composite material) composite material.

Secondly, without knowing more about Popeye's situation I don't think it is fair to castigate him for his question/idea. For all we know, he may be new to owning this boat, and it may be that the mast is not rigged properly and he doesn't know it simply through innocent ignorance. And while it's easy to say "build yourself a new mast" we have no idea whether this is a viable option for Popeye--we don't know what skills he may have, or whether he has the tools, the time, or the workspace to tackle such a job. And we sure don't know whether he could afford to have a professional build him a new mast.

Suggesting that the guy ought not own a wooden boat was a bit more than he deserved.

As for the carbon fiber issue, the point seems to be that if you are going to add a snythetic material to your mast to try and stiffen it, you'd better add enough to take the whole load. Fine. I'm sure that with the proper engineering this could be done. No one was suggesting to Popeye that he could run two or three carbon threads up his mast and solve his problem. Certainly not I! ;)

But IF a)rigging is not the problem, and b) the mast is structurally okay, and c) Popeye for some compelling reason can't build or buy a new mast, or re-rig the existing one, I can't see the harm in his asking about alternatives, our suggesting them, or his decision to investigate further should he so choose.

I guess I am befuddled as to how a mildly composite mast would make a boat any less wooden than, say, having bronze floors. Should we write nasty-grams to Larry and Lin Pardey and tell them they shouldn't own a wooden boat if they aren't going to build every piece out of wood? But gee, professionals have been building wooden boats with metal frames for about 100 years--so does that make them "traditional"? Or is it just an extended heresy? At what point does traditional give way to modernity?

[TomRobb]

The "S" in WEST stands for saturation but it ain't so. There's almost no "saturation" - it's really just coated. Increasted surface hardness maybe a bit. CPES "saturates" some it's claimed.

WECT isn't as memorable as WEST for a trademark. :D

And did someone say something about heresy or tradition? I guess I missed it - yet another senior moment. :eek:

[ 05-06-2002, 11:10 AM: Message edited by: TomRobb ]

[Joe ( Cold Spring on Hudson )]

Again Tom I have to disagree Im no chemist nor an engineer. I just know what I saw when I heated the wood and applied thinned with Acetone WEST System epoxy I WATCHED with my own eyes the epoxy get SUCKED into the wood it did not coat the wood it PENETRATED the wood the key I think was heating the wood then allowing it to cool wile the epoxy was drawn INTO the wood - All I know is it WORKED. Also may I add all this a wooden boat has got to be wooden boat is crap. In the level were talking about in composites its all molecules. What is marine grade Oakum plywood not WOOD? If you coat your wooden boat with Varnish to protect it from UV is it no longer wood since it has a coating on it ? - if you paint your hull with antifouling is it no longer a wooden boat ? - you purist give it a break its a Boat

[Scott Rosen]

Whoa!

Take it easy guys. No one is doing any serious thinking here. Read popeye's post carefully. He has a 34 foot wooden mast, 30 years old, on a ketch or yawl rig. It bends fore and aft when sailing under jib and jigger.

Here are my thoughts. There are probably two things going on simultaneously. One is a rigging problem; the other is a glue and joint problem.

First the rigging. The only way a sound mast will bend fore and aft under these circumstances is if the standing rigging is tuned or set up wrong. Fore and afte bending is prevented by the shrouds that attach from the port and starboard chainplates to the side of the mast, usually at the spreaders. I would expect three shrouds per side. One fore, one center and one aft. The shrouds, if properly tuned, are what will prevent the mast from bending. If the shrouds aren't tuned, then the mast will have too much movement at the spreaders and will bend under a high compressive load like jib and jigger. Probably the only reason it doesn't bend as much with the mainsail up is because the shape of the main holds the mast stiff in the fore and aft direction. So, item one. Check the tune of the rig, especially the shrouds.

Second, the glue. Thirty years is about the usable lifespan of mast glue. Most resourcinal glued masts that I know of start to separate at the joints between 20 and 30 years of age. Obviously, if the joints are loose, the mast will have less strength and will be much more susceptible to bending. Ultimately, this will lead to catasrophic failure. My recommendation is to pull the mast, strip the paint and/or varnish and inspect the joints very carefully, especially at the base, the top and the spreaders.

Glassing the mast will not address either of these problems.

By the way, on epoxy glue saturation--it is impossible to saturate sound wood with epoxy. It will penetrate just the very surface and then stop. If the wood in a mast isn't sound, you should replace it.

[popeyethesailor]

Well that was an interesting and informative string of posts (for the most part) thanks all.

First of all it is not a wood boat so maybe that puts me outa here right off.

Second of all I'm no brainiac but I'm not the idiot BC seems to think. I'm actually a quite capable and experienced sailor. Clearly I don't know much about these old fashioned materials.

Third. The mast is not over engineered at all. It is a friggin toothpick at the top.

Fourth. Yes it is a rigging problem. The lowers were set up by PO's such that a permanent bend above the spreaders was created. Only a hideous amount of tension in the aft lower will straighten it. So instead of a slight aft rake I have a vertical lower section with a bent upper section.

Fifth. I do not have the tools, space, or time to build myself a new mast. I'm just wondering if there is some way to resurect the old mast with a moderate input of money and time. If I were getting a new one I'd get an alluminum mast.

Thanks again everybody. It sounds like it's not really possible to get the strength I need out of this mast.

[TomRobb]

Joe CS on H,
Easy guy. There's no Purist rant here that I can see.
The point being made is that the suggested fix ain't. Popeye's going to have to dig a bit - get more data. If wrapping it in cloth worked who'd give a rat's patoot.
Sometimes the easy way out isn't. Sometimes we ought to listen to the obvious experts. (Not to me, I assure you)
All I really wondered about was the rigging
Sheesh :rolleyes:

[Joe ( Cold Spring on Hudson )]

OK informal test Im going to do the thinned WEST system epoxy capilary action test on a srap piece of old wood then Ill cut it in half and let you all know how far it penitrated

[Scott Rosen]

Joe,

Use sound wood and don't do the test on the endgrain.

You may find that the acetone will penetrate farther than the resin. It will also evaporate very fast, which can create the impression of absorbtion.

Then do another test. Take the West, thin it say 30 to 40%, and then let the mixture sit in a pot until it hardens. Tell us what the qualities of the hardened epoxy are.

[Joe ( Cold Spring on Hudson )]

I hope everyone knows since im new to this forum, that im not a militant flame poster - I just got a little irked at BC comment. I love this forum very diverse group of people and topics and a lifetimes worth of sailing and building knowledge. Im also fairly new at the restoration nd boat building process ( recently completed 1954 Dyre Dhow and a 20 year old Weekender 1 Gaff Riged Sloop - plywood construction waiting in the wings on the hard in my barn as well as a Stevenson design Cat Boat Im building from scratch ) - so I should keep quiet and listen more ( SWIMBO says that alot )

[Joe ( Cold Spring on Hudson )]

Hopefully my last post on this subject smile.gif Popeye if your going to go through the cost and bother of an Aluminum mast you may just check into a decent Local shipwright or even a great carpenter to rebuild you a wooden mast just give them your old mast as a template. It may save you a couple of bucks good aluminum masts are kinda pricey - and then there is the problem that Aluminum catastrophically fatiguing the wooden mast will last another 30 years way more than any aluminum mast

[mariner2k]

Popeye, Glass boat? You may want to look into a used mast. Aluminum or wood. A little refitting and you could be on your way. By the way, Cleek has been a welcome, knowledgable contributor for some time. Guess he just had a hair across his ass that day. It happens. Good luck.
Mariner

[Bob Cleek]

Like I said, it was Jack Daniels talking.. I musta blacked out! LOL

1. If the mast was designed for the boat, it is probably just fine, engineering wise.

2. If the glue is going, then take some wedges, carefully split her apart, clean her up and reglue.

3. Nothing wrong with carbon fibre. Great stuff for spars. HOWEVER, it is extremely expensive and takes a fair amount of techinical skill to fabricate. Slapping carbon fibre on top of wood is not the same as engineering a carbon fibre spar. You will see carbon fibre spars on "cost is no object" racers... that's about it.

4. Wrapping a wooden spar in anything isn't going to repair it. Never has, never will. Sometimes you have to fix it right or replace it. Wood doesn't last forever.

5. Find somebody around your neck of the woods who knows what they are doing to give you a hand. Looking at the thing is probably the best way to approach problem solving. An experienced eye can tell you if there is something wrong with your mast or whether the problem is rigging.

6. More time is spent thinking about how to fix anything wood on a boat than there ever is actually doing the job right, but the thinking first saves a whole bunch of time in the end.

[popeyethesailor]

Hey no big deal. I make posts like that too once in a while. Just to add to the background: my boat's a 1969 Mariner 31 ketch. I really like it, and it's not unlike wooden cruisers that came before it. It's not fast in light air or to windward, but it makes up for that in comfort, grace, and style; things that are hard to find in 31 footers of today.

Since you guys seem to know:

Which is heavier? wood or alluminum masts.

Which is stronger?

Which would cost more?

Which one would you prefer, and why?

This'll probably sound rediculous to some of you as well, but if you took a serious knock down or capsize and didn't lose the rig it seems like a wood mast would be good because of it's bouyancy.

Anyway, you should hear some of my strange ideas; innovation comes out of questioning accepted principles rather than following them. Now if I could turn some of my crazy ideas into a buck or two then I could go sailing.

[Paul Scheuer]

Would your fittings fit ? That might be a significant cost factor. If you go with aluminum, I'm sure someone here could use some of that nasty old 30-year-old hardware.

[Bob Cleek]

Strength isn't the issue, really, since the loading is primarily taken up by the rigging, not the spar, in the usual "Marconi" rigged mast. (Gaff spars are a bit different.) For rigging purposes, either material is more than adequate for the compression loads.

Bouyancy isn't a factor in a boat of any size. Note that some of the dinghy racers will put styrofoam in their spars to increase floatation when they dump them. There was one class of catamaran, I believe, that carried a big ball of foam at the masthead for that purpose.

I'd go with wood over aluminum for a cruiser. Aluminum is lighter, which is an advantage for a racer. However, for cruising, wood is far easier to work on, (particularly regarding fastenings and repairs) less succeptible to corrosion, and you can find a woodworker anywhere in the world you might find yourself, but you won't find "You weld-um aluminum?" in your foreign language phrase books.

[Nicholas Carey]

You might want to visit Brion Toss' forum 'Spartalk' at http://www.briontoss.com

For rigging issues, it's a useful place.

[paladin]

uuuh ...Fellas....ACETONE I believe is a cutting agent...not thinner....and the absolute max. that should be added to resin has been quoted by a couple of manufacturers as about 5% by volume....Long before the GUDJIN bros. came along we were doing this kinda stuff in L.A. and Alviso Slough and Thailand and we used Styrene monomer VERY carefully........

[Dwight]

I think we're missing something here. Did I hear that the mast has a permanent bend in it now? If its a fractional rig and the bend is above the rigging ,OK, but its a masthead rig, right? That means that rig tension will make the bend worse. You are going to have to get this thing straight to make it behave correctly, and doing so by bending it back and fiberglassing or whatever method is going to lock in stress, how much depending on how bad its bent. Nothing wrong with composite construction, or else you'd better stay out of buildings and off bridges. In the case of carbon fiber strands, the fiber on one side carries the tension, the wood on the other side carries the compression, still stiffer and stronger than before a properly designed and executed repair. Carbon fiber is a lot stronger for its size than you would think. As for covering the entire surface, I think you'd have to pay a lot of attention to detail around fittings to keep water out.

[Wild Wassa]

Good afternoon. How is your vang technique? I can induce all the problems mentioned in Popeyey's first posting, with bad technique. Can't we all. Do you play with the vang much. Is your top batten parallel with the boom?

I know you said you were a sailor Popeye, but how is your technique? Vangs have a significant effect on our rigs.

[ 05-31-2002, 10:29 PM: Message edited by: Wild Wassa ]

[bainbridgeisland]

I would like to point out a few things.

Wood masts can be as light or lighter than aluminum masts but they would be larger in diameter. This is because what counts is specific strength (compression strength/ density) and specific stiffness (stiffness/density). Some woods, like sitka spruce, have better properties than aluminum in this respect.

I think this boat has a rectangular mast, hollow box section. Thus scarfs or joints that have let go could be the problem. Check the varnish or paint at the edge of the scarfs and joints for tiny cracks. This would mean the scarf or joint is shifting around. Joints can be reglued.

If you must add strength or stiffness to your mast, I believe laminating more wood would be much better than trying to use fiberglass or carbon fiber. It would be easier, cheaper, with less technical risk and more in keeping with the original.

By the way, I find it hard to believe incorrect rig tension could "kink" a wooden mast. Though it could cause a warped section, a dramatic kink indicates a failure in the mast column. In other words look very closely for a damaged area of the mast.

Masts like this are easy to work on. They can be disassembled and then reassembled with new glue joints in a couple of days. Also more material can be easily added or removed if needed.

By the way, how much fore and aft bend are we talking about. I would expect up to 6" fore and aft bend on your boat. After 9" I may be mildly concerned. Wood is really a wonderful material in bending. In fact better than aluminum or carbon fiber as far as fatigue goes.

Rigging adjustmennt may cause the mast to appear to be "kinked". Here is how to check for this: Loosen all your shrouds so the mast can rock around on its step (best to loosen jumpers too if you have them). Hook a halyard or topping lift to the back of your boom. Put the boom on centerline and sheet down really hard. Now go site up the mast. If it has nice gentle bends, your mast is probably OK and rigging adjustment is the cause of the problem. If it has an abrupt kink in it your mast is probably damaged and needs repair.

[ 06-01-2002, 11:45 AM: Message edited by: bainbridgeisland ]

[Jon Agne]

Buy a catboat......the only reason the forestay is there is to prevent the telephone pole from falling on you if it breaks!